Re: Clarification of inheritance of fx, fy in gradients

Hi Erik,

Erik Dahlstrom wrote:
> Hi svg-wg,
> 
> I'm wondering if we should clarify the definition of the fx and fy 
> attributes[1] on the radialGradient element.
> 

I can understand why there would be some confusion. When in doubt it doesn't 
hurt to add extra wording for clarification.

> Scenario:
> - two radial gradients, the second one inheriting values from the first
> - the first gradient has cx specified to a value different from the 
> second gradient's cx
> - none of the gradients have fx or fy specified
> 
> Most implementations agree that the fx and fy values should not be 
> inherited from the first gradient (because the values were not 
> specified). Instead the fx and fy values (if not explicitly specified on 
> the first gradient) should be taken from the presentational value of cx 
> and cy on the second gradient.
> 

We could probably change the last sentence in the specification to include 
wording from your last sentence. For example:
[[
If attribute ‘fx’ is not specified, ‘fx’ will coincide with presentational value 
of ‘cx’ for the element whether the value for ‘cx’ was inherited or not. If the 
element references a radialGradient element that specifies a value for ‘fx’, 
then the value of ‘fx’ is inherited from the referenced radialGradient element.
]]

That might be a bit wordy, so feel free to modify it anyway you see fit.

> I've added a testcase covering this case[2] and would like for someone 
> to review it.
> 
> Preliminary testing:
> batik1.7 PASS
> Chromium PARTIAL
> Opera PARTIAL
> Firefox PARTIAL
> Inkscape FAIL
> 

I've reviewed the test and believe the rendered output by batik 1.7 to be correct.

This seems like an open-shut case, so we can probably briefly discuss it at the 
telcon in a few hours to finalise the wording and assign an action.

Cheers,

Anthony

> Cheers
> /Erik
> 
> [1] 
> http://dev.w3.org/SVG/profiles/1.1F2/publish/pservers.html#RadialGradientElementFXAttribute 
> 
> [2] 
> http://dev.w3.org/SVG/profiles/1.1F2/test/harness/htmlObject/pservers-grad-21-b.html 
> 
>

Received on Monday, 12 April 2010 08:38:47 UTC